
Cat Ba Island is in Ha Long Bay, Northern Vietnam. It is commonly used as an overnight hotel stop on tours to Ha Long Bay run by travel agents from Hanoi. Many tour operators include an option of trekking in the National Park or canoeing on three-day tours; shorter tours generally only stay overnight in the small town of Cat Ba (population about 8,000) or on boats moored in Cai Beo bay, about 2 km away from Cat Ba town.
Although there is much beauty to explore on the island, cat ba town itself is rather crumby. Lots of massage parlours offering happy ending and drunk chinese businessmen.
You can easily rent a motorbike from any hotel for $5 (standard) per day, but a quick walk along the main high street will offer perfectly serviceable automatic bikes for $3. There is tons to explore including Cat Ba National Park with gorgeous hikes that lead to isolated communities. Stunning, towering, green mountains surround.